CAAT box (also CAT box)
A conserved sequence found within the promoter region of the protein-encoding genes of many eukaryotic organisms. It has the consensus sequence GGCCAATCT; it occurs around 75 bases prior to the transcription initiation site; and it is one of several; sites for recognition and binding of regulatory proteins called transcription factors

Callus culture
A technique of tissue culture; it is usually on solidified medium and initiated  by inoculation of small explants or sections from established organ other cultures (the inocula). Callus culture is used as the basis for organogenic (shoot, root) cultures, cell cultures or proliferation of embryoids. Callus cultures can be indefinitely maintained through regular sub-culturing.

Calyx
(Gr. kalyx, a husk, cup) All the sepals of a flower considered collectively. The outermost whorl of flower parts

Cancer
Uncontrolled growth of the cells of a tissue or an organ in a multicellular organism. Cf oncogenesis.

Candidate gene
A gene whose function suggests that it may be involved in the genetic variation observed for  a particular trait, e.g., the gene for growth hormone is a candidate gene for body weight